This application relates generally to rotary grinding and shredding devices and, more particularly, to an interchangeable rotary block for mounting as part of an array of blocks on a rotor shaft, the block including at least one cutting blade mounting boss positioned in a geometric arrangement relative to the center bore of the block so that the block can be reversed on the rotor shaft to effectively double the number of available positions of each cutting blade. A plurality of blocks are stacked on the rotor shaft in an array to form a desired pattern of cutting blades along the length of the rotor assembly.
Apparatus for the grinding reduction of materials, for example waste woods or plastics are known in the art. Generally speaking, as shown in FIGS. 1, 2, and 3 the apparatus 10 includes a rotor assembly 12 mounted in a frame 14 adjacent a material inlet 16, driven by a motor 18 and belt 20. The rotor assembly 12 includes a shaft 22 having cutting blades 24 mounted thereon. In some embodiments, a hydraulic ram 26 is included to urges the material toward the rotor assembly 12. Often, in prior art, the rotor assembly, is machined from a solid billet of steel. Individual cutting blades are machined into the surface of the rotor at discrete positions along the length of the rotor. In other embodiments, the rotor includes bosses for mounting cutting blades. The cutting blades, generally replaceable, are bolted or otherwise mounted on the bosses. The cutting blade mounting bosses arc machined along the length of the rotor in a desired pattern so that the attached cutting blades are positioned in a corresponding pattern.
Machining the rotor from a solid billet of metal, whether it includes cutting blades or bosses for replaceable blades, has obvious drawbacks. The process is expensive and labor intensive. Furthermore, the cutting blade pattern of the resulting rotor cannot be changed. Inventors have made attempts to overcome these disadvantages. For example, U.S. Pat. No. 5,474,239 to Williams, Jr. et al. discloses a shaft driven set of blocks in which each block has cutting blades in circumferentially spaced relation. The blocks are keyed to the shaft to form a predetermined cutting blade arrangement. Each block has its own keyway which receives a common key extended along the length of the rotor shaft. Each adjacent block has its keyway rotated to a position such that the blades on the block are offset from the blades on adjacent blocks by a predetermined angular relationship.
It will be appreciated, however, that each block must be individually constructed for a specific position on the shaft and, although the design functions well for its intended purposes, the versatility of the blocks is limited. It would be advantageous, therefore, to have a shaft and block arrangement wherein each block can be mounted on the shaft in any of a plurality of positions, and is not limited by the position of a keyway. Furthermore, it would be advantageous if the block can be reversed on the shaft to effectively double the number of possible positions of the block relative to the number of sides on the shaft and, therefore, double the number of possible positions of the cutting blades on the surface of the block relative to the shaft configuration (number of sides).